# API Test Designer

> Design API-level test coverage from an endpoint or contract. Use when a tester says "design API tests for POST /orders", "test this endpoint", or pastes an OpenAPI / contract snippet and wants coverage mapped. Produces a coverage matrix across happy path, schema validation, auth/permission, negative inputs, boundary values, and idempotency, each case tied to the contract, then stops for review before cases are built.

- Skill: `pramoddutta/api-test-designer` (Agent Skill)
- Install (CLI): `npx skillmds@latest add pramoddutta/api-test-designer`
- Raw SKILL.md: https://api.skillmd.com/api/skills/pramoddutta/api-test-designer/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Integrations & APIs
- License: MIT
- Author: PramodDutta (https://skillmd.com/u/pramoddutta)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/pramoddutta/api-test-designer

---


# API Test Designer

You map the **coverage an endpoint deserves** at the contract level — status codes,
schemas, permissions, and edge inputs — one layer above written request cases.

## When to use
- An endpoint, OpenAPI spec, or contract snippet needs test coverage designed.
- Someone asks "what should we test on this API besides the happy path?"
- A new or changed endpoint is entering the regression pack and needs a matrix.

## Workflow
1. **Read the contract.** Capture method, path, request schema, response schemas per status,
   auth requirements, and stated constraints. If the contract is missing, ask for it —
   do not assume field names, status codes, or auth rules.
2. **Design across dimensions.** Generate cases only where the contract supports them:
   documented success responses and bodies, schema validation (required/optional/types),
   auth and permissions, negative inputs and errors, boundaries, and documented idempotency,
   retry, or concurrency guarantees. Mark an applicable but unspecified outcome unknown.
3. **Specify assertions.** For each case note expected status, key response fields, and any
   side effect (record created, event emitted) to verify.
4. **Trace.** Map each case to the contract element or requirement it covers; flag untested
   status codes or fields.
5. **HUMAN REVIEW GATE (mandatory).** Present the matrix as a draft. Note assumptions about
   auth, schema, and side effects. Ask for confirmation before cases are written or automated.

## Output shape
```
## API Test Design — <METHOD> <path>
| ID   | Dimension     | Request                | Expected status | Assert            |
| AT-1 | happy path    | contract-valid body    | contract-defined | body matches schema |
| AT-2 | schema        | missing required field | contract-defined | documented error  |
| AT-3 | auth          | no token               | contract-defined | documented denial |
| AT-4 | boundary      | max-length field       | contract-defined | documented result |
| AT-5 | idempotency   | same request x2        | contract-defined | documented invariant |
Coverage note: untested status codes / fields
--- HUMAN REVIEW GATE ---
Unknown contract outcomes / "Approve before these become request cases"
```

## Guardrails
- Never invent a field, status code, or auth rule the contract does not state — flag the unknown.
- Keep every expected status and error shape `contract-defined` until a supplied contract
  provides the exact value; examples are not requirements.
- Design intent only; concrete request bodies and data come from the data generator.
- Do not assume a side effect occurred; every effect is an assertion to verify, not a given.
- The matrix is a draft until a human confirms the contract reading.